Fabrication and characterization of self-assembled Nafion–SiO2–ePTFE composite membrane of PEM fuel cell

Self-assembled Nafion–SiO2 polymer electrolyte membrane enhanced by ePTFE matrix was prepared in this study. The original ePTFE membrane was chemically modified before the preparation by sodium–naphthalene treatment to increase the wetting compatibility between self-assembled Nafion–SiO2 dispersions and ePTFE matrix. Compared to the freestanding Nafion–SiO2 membrane, the physical strength of the as-resulting ePTFE PEM was significantly improved from ∼20 MPa to 32 MPa. The area conductance of the as-resulting membrane was also promoted to ∼40 S cm−2 and ∼50 S cm−2, respectively at 60 °C and 100 °C with the decrease of the membrane thickness (15 μm) in 50% RH gas atmosphere. With the presence of self-assembled silica particles, the self-assembled Nafion–SiO2–ePTFE composite membrane possesses excellent water-retention property. At elevated operating temperature of 100 °C, 50% RH, 0 back pressure, the output voltage of the Nafion–SiO2–ePTFE fuel cell was 0.603 V under condition of 600 mA cm−2, 0.105 V higher than that of the freestanding Nafion/ePTFE fuel cell under the same condition.